Books for the REAL Olympiads:
             The above books are recommended for Privately held National  Math Competitions like SOF-IMO, Siverzone iOM, Unified Council’s NSTSE etc and also great for school curriculum. The Terry Chew’s books listed above are great for Singapore Math Olympiads and highly recommended to practice non-routine challenging math.
Further, if your child really love mathematics and you may be planning for his/her higher education in mathematical sciences, Computer sciences , then you may need a specific plan to reach the highest seats of knowledge in India and abroad. You need to get into the beauty of solving non-routine mathematical problems.
The REAL Mathematical Olympiads play a very important role in this journey. Usually the best universities hold Math Olympiad (the Real one) success in highest esteem. To gradually prepare the student for the Real Math Olympiad is a challenge for both teachers and parents.
It is hard to find great books for elementary school kids. The following books are some happy exceptions. I would highly recommend teachers, parents and the students to possess at-least two of the following books and work on them cover to cover, if you want your child to fall exceptionally in love with Mathematics. They are available from Amazon and links are given below:
1)  Math Circle by the Bay: Topics for Grades 1-5
2) Math Circles for Elementary School Students
3) Math from Three to Seven
4) Mathematics Can Be Fun